Foam Diagnostic Kit

Why your pours are foamy — and the fastest path to a fix

Most foam complaints trace to one of four root causes: temperature drift, wrong pressure, dirty lines, or worn faucet seals. Diagnose in that order. You'll eliminate the cheap fixes first and never chase the wrong fault.

1. Check the temperature first

Beer should pour at 36–40°F at the faucet. Warmer than 40°F and CO₂ starts breaking out of solution before the beer hits the glass — every degree above target makes the foam exponentially worse.

• Beer above 40°F at the faucet → glycol chiller running warm, or an insulation gap in the trunk line
• Beer cold in the keg but warm at the faucet → the tower isn't being chilled (dead glycol jumper, fan trunkline failure, or short-circuited recirculation)

Tool: infrared thermometer pointed at the spout right before the pour.

2. Verify the pressure

Every beer-style-by-temperature combination has a balanced CO₂ pressure. Most American lagers at 38°F want 10–12 PSI; British ales lower; nitro stouts use a 75/25 nitrogen blend at 28–32 PSI. If your gauge has drifted, the math is wrong from the start.

• Regulator reads 10 PSI but actual is 14 → over-foam from gauge drift
• Gauge sticks or hesitates → replace the gauge or rebuild the regulator

Tool: verify with a known-good test gauge or temporarily swap in a fresh regulator.

3. Clean the lines

Beer lines build up biofilm — yeast and bacteria — over weeks. Biofilm creates microscopic nucleation sites where CO₂ breaks out of solution, so every pour foams. Clean lines should look glass-smooth on the inside.

• Lines not cleaned in 2+ weeks → almost certainly the cause
• Visible film when you backflush → confirmed, run a full alkaline-then-acid cycle

Tools: alkaline cleaner (kills biofilm), a low-foaming acid sanitizer (post-clean — high-foaming sanitizer leaves residue that contributes back to foam), and a pressurized cleaning vessel with a native D-system Sanke adapter so you can flush every line under working pressure without breaking the keg seal.

4. Inspect the faucet

Faucet seals — the O-ring at the lever and the seat seal at the spout — harden and crack from constant CO₂ exposure and temperature cycling. Worn seals let air past during the pour. Air + beer = foam.

• Slow drip from the faucet when closed → seat seal failing
• Pour starts smooth then turns foamy mid-glass → lever seal failing

Tools: faucet brush set to physically clean, plus a rebuild kit. Most commercial faucets need a rebuild every 12–18 months under heavy use.

What's in this kit

• Temperature diagnostic — UEi infrared thermometer, point-and-shoot to the spout
• Line cleaning — Micro Matic MM-B68 alkaline cleaner + Micro Matic 5L pressurized cleaning kit with D-system Sanke adapter built in
• Line sanitizing — Five Star SaniClean (low-foaming, won't contribute residue back to the foam problem)
• Faucet maintenance — Intertap-compatible faucet brush + a faucet seal rebuild kit

What's NOT in this kit but you may still need: a digital CO₂ test gauge (we don't currently stock a generic — call our techs and we'll spec one for your system) and replacement glycol if you're chasing a chiller fault.

Most foam issues resolve at Steps 1–3 alone. Step 4 is for when line cleaning doesn't fully clear the symptom.

Still foaming after working through this? Call us at 888-964-4239. We install draft systems for a living and usually diagnose by phone in five minutes.